A macro definition is a named sequence of statements you can call
with a macro instruction. When it is called, the assembler processes
and normally generates assembler language statements from the definition
into the source module. The statements generated can be:
Copied directly from the definition
Modified by parameter values and other values in variable symbols
before generation
Manipulated by internal macro processing to change the sequence
in which they are generated
You can define your own macro definitions in which any combination
of these three processes can occur. Some macro definitions, like
some of those used for system generation, do not generate assembler
language statements, but do only internal processing.
A macro definition provides the assembler with:
The name of the macro
The parameters used in the macro
The sequence of statements the assembler generates when the macro
instruction appears in the source program.
Every macro definition consists of a macro definition header statement (MACRO), a macro
instruction prototype statement, one or more assembler language statements, and a macro definition
trailer statement (MEND), as shown in Figure 1. Figure 1. Parts of a macro definition
The macro definition header and trailer
statements (MACRO and MEND) indicate to the assembler the beginning and end of a macro definition
(see 1 in Figure 1).
The macro instruction prototype statement names the macro (see 2 in
Figure 1), and declares its parameters (see
3 in Figure 1). In the operand field of
the macro instruction, you can assign values (see 4 in Figure 1) to the parameters declared for the called macro definition.
The body of a macro definition (see 5 in Figure 1) contains the statements that are generated when you call the
macro. These statements are called model statements; they are normally interspersed with
conditional assembly statements or other processing statements.
